Opponents of housing development in Hong Kong's cherished country parks are on the move.

About 1,000 people took to a Tai Tam hiking trail on Sunday in protest after development chief Paul Chan Mo-po floated the idea of allowing homes to be built in the previously untouchable rural havens.

But two veteran town planners have taken a different approach: digging out suitable sites outside the parks, as proof the government isn't trying hard enough. Investigations by the South China Morning Post have also turned up sites long earmarked for development which remain vacant.

"We do have land. It's just the government is taking the easy way out," said Ng Cho-nam, a professor of urban planning at the University of Hong Kong, who spent six years studying rural development plans for the Town Planning Board until 2010.

Professor Chau Kwai-cheong, a member of the Town Planning Board and a Chinese University academic, doesn't entirely agree.

"It's not easy at all," he said. "I don't think there would be less opposition if parks are downsized, compared to developing new towns on agricultural land."

But one thing they do agree on is that there is plentiful green belt land of lower ecological value than the parks that could easily be developed. They also spelt out conditions for the development of green belt sites, set up as a buffer between the urban areas and the countryside.

The Post was also able to identify inefficient use of land in the form of dozens of sites earmarked as comprehensive developments areas, or CDAs, which have lain idle for more than 10 years after being zoned for housing and mixed-use development.

The debate on slicing off country park land for housing has raged since Chan made his remarks more than a month ago, with some developers, property experts and pro-establishment lawmakers backing the idea.

But the outcry from the community at large has put other ministers off backing Chan's suggestion. Chief Executive Leung Chun-ying, who pledged in his manifesto to defend the country parks, said there was no change in the government's position.

The investigation of land supply by the Post and the experts was prompted in part by a mistake Chan made in the blog post in which he floated the idea.

Chan wrote that country parks represented 70 per cent of the city's territory, which includes Hong Kong Island, Kowloon, New Territories and all outlying islands.

The true figure for parkland is 40 per cent , with the remaining 30 per cent taken up by wild, uncontrolled woodland, shrubland, grassland, wetlands, barren land and bodies of water. That statistic begs the obvious question: is the city making good enough use of the remaining 30 per cent?

It may sound like a matter of simple mathematics. But data made available by the Planning Department does not provide a straight answer.

A land utilisation map, available from the Lands Department, shows existing land uses based on satellite images. But the map does not give details of what the land is zoned for. Without that information, it is difficult to identify where new housing could go.

For further details the Post trawled through more than 100 outline zoning maps. This made it possible to see how urban, green belt and country park land slotted together

Hong Kong has a total of 153.9 sq km of green belt areas, taking up 13.8 per cent of the city's land. The official definition says such areas define the limits of urban and suburban development and are characterised by features such as foothills, knolls and woodland. As well as containing the urban sprawl, they offer recreational outlets for the enjoyment of the community.

The zoning is also intended to conserve the natural environment and neighbouring sites of ecological value, including country parks and sites of special scientific interest. Therefore, there is a general presumption against development on green belt sites, except on a tiny scale and according to conditions set by the Town Planning Board.

Significant areas

Planning Department figures show that a total of 98 developments, all consisting of village houses, were approved on green belt areas over the past five years. The developments occupy just two hectares of land.

"We are not supposed to build on these areas," Ng said. But at the Post's request, he singled out a few possible sites for housing.

"My message is that there are other options before looking into the country parks," he said.

Chau, who chaired the Country and Marine Parks Board between 2003 and 2007, said choosing green belt sites for development required care.

"We can only consider building on seriously eroded granite landscapes and must avoid the ecologically sensitive sites, like fung shui woods," he said.

In total, the two urban planners identified three significant areas of the northern New Territories that could be considered for the development of flats: Ngau Tam Mei in Yuen Long, Hung Lung Hang in northern Sheung Shui and Chau Tau, to the south of the Lok Ma Chau border crossing.

More than 34 per cent of the land - 316.7 hectares - in Ngau Tam Mei has been zoned as green belt, at Shek Wu Wai, San Tin Barracks and to the south of Ngau Tam Mei Valley. Next to the green belt land is a large area used for open-air storage, covering about 90 hectares, and two sites zoned for mixed development, totalling 53 hectares, which have been left empty for 18 years.

The site's present zoning means it could, with the permission of the board, be used for golf courses, firing ranges, crematoriums or columbariums.

As for Hung Lung Hang, a popular spot for waste collection and sorting operations, more than 245 hectares of land is designated as green belt - covering mountain ridges from Tsung Shan, Ma Tau Leung, High Hill, Cham Shan and Cheung Po Tau. The area is less sensitive, as the government suggested in its outline zoning plan that small-scale housing developments may be permitted with or without conditions.

Green belt sites around Chau Tau make up 188.6 hectares of the San Tin area, where flats are one type of development that can be approved by the board.

Overall, the three sites the professors identified would yield 750 hectares of land, more than twice the area of the former Kai Tak airport site, which will eventually yield more than 16,000 flats as well as a new stadium and the cruise terminal, already open.

The three sites are not remote or inaccessible and transport links could be expanded if the government's railway development strategy is fully realised.

Both Chau Tau and Ngau Tam Mei are sites for stations on the proposed Northern Link from Kam Sheung Road Station on the West Rail Line via Sheung Shui on the East Rail Line to Lok Ma Chau.

Despite these sites' acceptability, the two professors urged strict conditions be put in place for building flats on green belt areas: it must be considered only after brownfield sites are exhausted; only public flats should be built, and development should be of an appropriate scale and include sufficient community facilities. Lastly, the development must be accompanied by an effective population policy to ensure there will not be an endless need for more housing.

"The government should first develop brownfield sites before considering building on the green belt," Ng said. Brownfield sites are those formerly for industrial or commercial use but now being used for open storage, car repair workshops or holding areas for cargo. Such sites are scattered across Yuen Long, Tuen Mun and Sheung Shui. Such activities have spread fast, as land owners look to take advantage of lax government enforcement by making profitable use of unused agricultural land.

While the Lands Department cannot say how much land close to the border is being used to store cargo, it said 471 hectares of land had been zoned for open storage. Satellite images, however, show cargo storage occupies an area more than three times that size - some 16 sq km.

Endless task

The Post's review of the status of CDA sites also found at least 13 undeveloped sites in the New Territories, with a total size of 119 hectares. The figure excludes sites earmarked for the development of new towns in Hung Shui Kiu and Kwu Tung North.

Chau also put forward another suggestion, which touches on the thorny issue of village houses to which all indigenous male villagers in the New Territories are entitled. "Villagers have a role to play in saving land resources too," he said. "Many indigenous villagers have become urban dwellers and their linkage to villages no longer exists."

He said the government should encourage villagers to redevelop villages, including more than 100 hectares in Pat Heung, into a new town of high-rises with modern facilities. His suggestion echoes an idea put forward by rural strongman and Heung Yee Kuk chairman Lau Wong-fat.

Chau urged the government to take a step back and take a holistic approach to the housing problem. "With no offence and discrimination, we should find out who is living in subdivided flats and for whom we are really sourcing land," said Chau. "If we turn a blind eye to the rising number of new immigrants who are comparatively reliant [on government help] and receive little education, the quest for land and flat construction would become an endless task."

Secretary for Transport and Housing Anthony Cheung Bing-leung said the government's target of building 470,000 flats in the next decade was, in part, meant to satisfy demand from those living in substandard conditions. But the government has yet to complete its population policy, which is intended to address issues including the ageing population and shrinking workforce.

Whatever the results of the policy, which is due to go out for public consultation this month, experts agree taking short cuts to solve land woes is not the answer.

"The parks should be saved for future generations," said Dr Wong Fook-yee, a retired senior official who managed the city's country parks for almost 30 years. "Our decision determines how they will get on with their life.

"While birds and animals do not have a voice, can you imagine the US government suggesting downsizing Yellowstone National Park for flats?"

This article appeared in the South China Morning Post print edition as: